My 3T 30mm wide leaf is 21.51kV. Only suitable for a recumbent or 16 inch wheeled bike, for sure. In a 20 inch rim, it will do 50mph on 14S ( 50.4v ). I imagine the 3T 35mm wide leaf hub would be equally crazy. 4T is as low as you should go.

I'm looking for some thoughts and opinions. I've been running a leafbike 1500W for over a year now and I'm pretty happy with it but I like the idea of more lbs of thrust and greater efficiency (cooler running motor) of a slightly smaller wheel.

I also currently use field/flux weakening to achieve top speeds of approximately 62 kmph on flat and a torque increase at higher rpm. If I went with a 24 inch wheel and increase flux weakening even more; would it be worth the effort or should I just stick to my 26 inch wheel?

Flux weakening provides an efficiency hit, from what i've read.. more volts, or different winding, is much better.
Unfortunately you won't notice much of a difference between a 26 inch and 24 inch wheel. I've done it and wasn't super impressed.

Thanks for the reply neptronix. I am using the 5T winding. The 5T was my choice mainly because I was somewhat limited with my max battery amps I could deliver but I am now running enough for 80A peak discharge.

Sorry, but i can't make a comparison because my original motor was in a 26", whereas this one will be in a 20" or maybe even smaller..
Generally the less motor, the less drag. You can see this in the ebikes.ca listings that include iron loss figures.

One thing you should consider is the tire selection. It's not so great for 24" wheels. See if there is a suitable tire before you take the leap..

Damn, I was just playing with the simulator. I knew that a lower turn count would give more rpm/volt but I didn't realize it would also give a broader power band like running a higher voltage. Looks like it might actually be worth switching to a 4T in a 24 inch wheel.

I believe the casette version has a 12mm axle on at least one side. I wouldn't recommend buying it, unless they've revised the interface to have two 14mm axles. Otherwise you'd be best advised to run the motor closer to what it's rated for, rather than what it's actually capable of.

I believe the casette version has a 12mm axle on at least one side. I wouldn't recommend buying it, unless they've revised the interface to have two 14mm axles. Otherwise you'd be best advised to run the motor closer to what it's rated for, rather than what it's actually capable of.

I want to see them make a variant of this motor where the cassette won't risk bending the axle or cracking the motor case when the rider is pedaling hard with the chain in the smaller cogs towards the outside of the axle.

I want to see them make a variant of this motor where the cassette won't risk bending the axle or cracking the motor case when the rider is pedaling hard with the chain in the smaller cogs towards the outside of the axle.

Any new data on the 1 kW version of this motor, such as what kind of peak power one can reasonably expect from it without destroying it?

Wish i could provide some. My application will be in a 20" wheel in a very aerodynamic ( recumbent ) chassis so whatever result i have won't apply to most folks thinking of using the motor.

I can tell you from opening up the 30mm version is that it's as finely constructed as the 35mm motor i bought in late 2014 that started this thread. I think we can expect the dyno data that leafbike has presented us to be as accurate as it was for the 35mm.

Wish i could provide some. My application will be in a 20" wheel in a very aerodynamic ( recumbent ) chassis so whatever result i have won't apply to most folks thinking of using the motor.

Those results will apply to my project quite nicely though.

With the new job I obtained, I'm planning on adding a rear suspension(already have front suspension) and going to 16" moped rims all around and possibly Mitas MC2 tires all around(comparable in diameter to 20" bicycle tires/rims), with a Schlumpf HS drive on a 152mm 26/39/52T crankset and 34-11T rear gearing. Either the 1000W or 1500W motor set up with a 3T wind and a 20s4p pack of Panasonic 2170 cells, combined with gearing that would allow climbing steep hills un-powered at 3 mph and 60 cadence and barreling down the highway at 85 mph and 120 cadence, and everything in between, with human power capable of adding to the propulsion at all operating points, would make this vehicle a viable car replacement that performs in a car-like manner, that could be operated like a velomobile with the drive system completely disabled, operate silently with the drive system enabled, and strongly resemble AND FUNCTION LIKE a normal velomobile to the cops with all the electrical guts hidden out of view thanks to the use of a hub motor.

Personally, I'm leaning towards the 1000W motor more than the 1500W motor in spite of the reduced possible power, mainly for the lowered resistance while pedaling unpowered as well as the reduced weight/inertia losses. You don't need much power to go fast in a velomobile, and my next design is going to be significantly more efficient than my last, possibly only needing 6 kW to do 90 mph. Now whether the vehicle would be safe or the motor reliable at such a speed would be another argument altogether, as I don't plan to be pushing its limitations on a regular basis, but have 30-45 mph cruising speeds in mind as the default mode of operation(with a Panasonic 2170 20s4p battery pack plus my pedal input in such a usage case, I would easily have a range in excess of 150 miles plus the ability to cruise on flat ground at 20+ mph with the motor off when the pack runs dead, and with recharge/meal stops along the way, possibly could cover 500 miles a day in such a vehicle for pennies worth of electricity and a few dollars of food/water).

I can tell you from opening up the 30mm version is that it's as finely constructed as the 35mm motor i bought in late 2014 that started this thread. I think we can expect the dyno data that leafbike has presented us to be as accurate as it was for the 35mm.

My guess then is that the 1 kW motor may be good for 3 kW peak unmodified, and if it is similarly under-rated like its larger brother, perhaps 1.5 kW continuous. Which may mean with fans/ferrofluid/holes/other mods, possibly up to 6-7 kW peak for short bursts and 2 kW continuous.

I'm looking forward to your results and to you completing this project.

That would be great news. I'd only need about 20-25 seconds to accelerate to a 90 mph top speed in such a vehicle with that kind of power on tap, and probably wouldn't want to keep at that speed for very long...

Really only one way to find out though. Were money no object for me, I'd gladly destroy components just to find their limits and publish the findings.

Playing with the ebikes.ca simulator, i realized that a 30mm wide DD is enough to push my 100lbs semi-faired recumbent up some ~10 mile 7% grades. it is the bare minimum of what i need in a long distance vehicle that peaks at 50mph. If i ddin't live next to the continental divide, a 27mm hub work and be more ideal ( less eddy currents ), except that takeoff power just won't be as strong.

Unfortunately leaf does NOT offer the lighter 27mm, so you'd have to go with MXUS or 9C and pray they'll provide you at least a 4T winding..

My 3T 30mm motor is wound a bit too fast for my vehicle, but a 3T is probably just the ticket for what you're looking to do. On 72v it will hit highway speeds. I don't have the battery to feed it's amp needs!